Many machine tools are configured so that workpieces are machined in an internal area closed by a cover, thereby securing the security. Although the cover has a window, an operator can visually recognize only a limited portion through this window, and therefore, there is a limitation in monitoring the machining status of a workpiece.
Therefore, as described in the Japanese Unexamined Patent Application Publication No. 2005-190102, for example, a camera is arranged in such an internal area in the machine tool and images obtained from this camera are displayed on a display device, thereby the operator can check the machining status of a workpiece with the displayed images.